From 1007913a930c9ddb2106e1b36211a695a57a4ba0 Mon Sep 17 00:00:00 2001
From: Neil Beukes <neilbeukes8@gmail.com>
Date: Tue, 26 May 2026 15:10:32 +0000
Subject: [PATCH 01/10] working on merge transfer

---
 .../InvenTree/common/setting/system.py        |   9 ++
 src/backend/InvenTree/stock/models.py         |  44 +++++++-
 src/backend/InvenTree/stock/serializers.py    |  40 ++++++-
 src/backend/InvenTree/stock/test_api.py       | 100 ++++++++++++++++++
 src/backend/InvenTree/stock/tests.py          |  12 +++
 src/frontend/src/forms/StockForms.tsx         |  23 +++-
 .../pages/Index/Settings/SystemSettings.tsx   |   1 +
 src/frontend/vite.config.ts                   |   1 +
 8 files changed, 225 insertions(+), 5 deletions(-)

diff --git a/src/backend/InvenTree/common/setting/system.py b/src/backend/InvenTree/common/setting/system.py
index c646aa843d0c..ba9e60e87c97 100644
--- a/src/backend/InvenTree/common/setting/system.py
+++ b/src/backend/InvenTree/common/setting/system.py
@@ -787,6 +787,15 @@ class SystemSetId:
         'default': False,
         'validator': bool,
     },
+    'STOCK_MERGE_ON_TRANSFER': {
+        'name': _('Merge stock with existing stock on transfer'),
+        'description': _(
+            'Default: when transferring stock, merge into an existing lot at the '
+            'destination if possible (uses the same rules as manual stock merge)'
+        ),
+        'default': False,
+        'validator': bool,
+    },
     'BUILDORDER_REFERENCE_PATTERN': {
         'name': _('Build Order Reference Pattern'),
         'description': _('Required pattern for generating Build Order reference field'),
diff --git a/src/backend/InvenTree/stock/models.py b/src/backend/InvenTree/stock/models.py
index 040daee86ef3..d3274e6a47d9 100644
--- a/src/backend/InvenTree/stock/models.py
+++ b/src/backend/InvenTree/stock/models.py
@@ -2179,6 +2179,34 @@ def can_merge(self, other=None, raise_error=False, **kwargs):
 
         return True
 
+    def find_merge_target(self, location):
+        """Find an existing stock item at *location* that can absorb this item."""
+        if location is None:
+            return None
+
+        candidates = list(
+            StockItem.objects.filter(part=self.part, location=location)
+            .exclude(pk=self.pk)
+            .order_by('pk')
+        )
+
+        if not candidates:
+            return None
+
+        if self.batch:
+            batch_matches = [c for c in candidates if c.batch == self.batch]
+            search_order = batch_matches + [
+                c for c in candidates if c not in batch_matches
+            ]
+        else:
+            search_order = candidates
+
+        for target in search_order:
+            if target.can_merge(other=self, raise_error=False):
+                return target
+
+        return None
+
     @transaction.atomic
     def merge_stock_items(self, other_items, raise_error=False, **kwargs):
         """Merge another stock item into this one; the two become one!
@@ -2186,7 +2214,7 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
         *This* stock item subsumes the other, which is essentially deleted:
 
         - The quantity of this StockItem is increased
-        - Tracking history for the *other* item is deleted
+        - Tracking history for the *other* item is copied to this item
         - Any allocations (build order, sales order) are moved to this StockItem
         """
         if isinstance(other_items, StockItem):
@@ -2200,7 +2228,7 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
 
         user = kwargs.get('user')
         location = kwargs.get('location', self.location)
-        notes = kwargs.get('notes')
+        notes = kwargs.get('notes') or ''
 
         parent_id = self.parent.pk if self.parent else None
 
@@ -2242,6 +2270,18 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
                 self.parent = None
                 self.save()
 
+            self.copyHistoryFrom(other)
+
+            if other.location:
+                location_note = _('Transferred from %(location)s') % {
+                    'location': other.location.pathstring
+                }
+
+                if notes:
+                    notes = f'{notes}\n{location_note}'
+                else:
+                    notes = location_note
+
             other.delete()
 
         self.add_tracking_entry(
diff --git a/src/backend/InvenTree/stock/serializers.py b/src/backend/InvenTree/stock/serializers.py
index 570b4f7e518e..6b857ac4033c 100644
--- a/src/backend/InvenTree/stock/serializers.py
+++ b/src/backend/InvenTree/stock/serializers.py
@@ -1829,7 +1829,7 @@ class StockTransferSerializer(StockAdjustmentSerializer):
     class Meta:
         """Metaclass options."""
 
-        fields = ['items', 'notes', 'location']
+        fields = ['items', 'notes', 'location', 'merge']
 
     items = StockAdjustmentItemSerializer(many=True, require_non_zero=True)
 
@@ -1842,6 +1842,15 @@ class Meta:
         help_text=_('Destination stock location'),
     )
 
+    merge = serializers.BooleanField(
+        default=False,
+        required=False,
+        label=_('Merge into existing stock'),
+        help_text=_(
+            'Merge transferred items into existing stock items at the destination if possible'
+        ),
+    )
+
     def save(self):
         """Transfer stock."""
         request = self.context['request']
@@ -1851,6 +1860,7 @@ def save(self):
         items = data['items']
         notes = data.get('notes', '')
         location = data['location']
+        merge = data.get('merge', False)
 
         with transaction.atomic():
             for item in items:
@@ -1865,6 +1875,34 @@ def save(self):
                     if field_value := item.get(field_name, None):
                         kwargs[field_name] = field_value
 
+                if merge:
+                    target = stock_item.find_merge_target(location)
+
+                    if target:
+                        merge_kwargs = {
+                            'location': location,
+                            'notes': notes,
+                            'user': request.user,
+                            **kwargs,
+                        }
+
+                        if quantity < stock_item.quantity:
+                            piece = stock_item.splitStock(
+                                quantity,
+                                location,
+                                request.user,
+                                notes=notes,
+                                allow_production=True,
+                                **kwargs,
+                            )
+                            target.merge_stock_items([piece], **merge_kwargs)
+                        else:
+                            target.merge_stock_items(
+                                [stock_item], **merge_kwargs
+                            )
+
+                        continue
+
                 stock_item.move(
                     location, notes, request.user, quantity=quantity, **kwargs
                 )
diff --git a/src/backend/InvenTree/stock/test_api.py b/src/backend/InvenTree/stock/test_api.py
index d274fffafa9d..a4961d829d87 100644
--- a/src/backend/InvenTree/stock/test_api.py
+++ b/src/backend/InvenTree/stock/test_api.py
@@ -2154,6 +2154,106 @@ def test_transfer(self):
         )
 
 
+class StockTransferMergeTest(StockAPITestCase):
+    """Tests for optional merge-on-transfer behavior."""
+
+    def setUp(self):
+        """Set up stock items for merge transfer tests."""
+        super().setUp()
+
+        self.part = Part.objects.get(pk=1)
+        self.dest = StockLocation.objects.get(pk=2)
+        self.source_loc = StockLocation.objects.get(pk=5)
+        self.url = reverse('api-stock-transfer')
+
+    def test_transfer_without_merge_creates_separate_lot(self):
+        """Transfer without merge leaves multiple stock rows at destination."""
+        existing = StockItem.objects.create(
+            part=self.part, location=self.dest, quantity=100
+        )
+        incoming = StockItem.objects.create(
+            part=self.part, location=self.source_loc, quantity=50
+        )
+
+        self.post(
+            self.url,
+            {
+                'items': [{'pk': incoming.pk, 'quantity': 50}],
+                'location': self.dest.pk,
+                'merge': False,
+            },
+            expected_code=201,
+        )
+
+        self.assertEqual(
+            StockItem.objects.filter(part=self.part, location=self.dest).count(), 2
+        )
+
+        existing.refresh_from_db()
+        self.assertEqual(existing.quantity, 100)
+
+    def test_transfer_with_merge_combines_lots(self):
+        """Transfer with merge combines into an existing compatible lot."""
+        existing = StockItem.objects.create(
+            part=self.part, location=self.dest, quantity=100
+        )
+        incoming = StockItem.objects.create(
+            part=self.part, location=self.source_loc, quantity=50
+        )
+
+        self.post(
+            self.url,
+            {
+                'items': [{'pk': incoming.pk, 'quantity': 50}],
+                'location': self.dest.pk,
+                'merge': True,
+            },
+            expected_code=201,
+        )
+
+        self.assertEqual(
+            StockItem.objects.filter(part=self.part, location=self.dest).count(), 1
+        )
+
+        existing.refresh_from_db()
+        self.assertEqual(existing.quantity, 150)
+        self.assertFalse(StockItem.objects.filter(pk=incoming.pk).exists())
+
+    def test_transfer_merge_preserves_tracking(self):
+        """Transfer merge copies tracking history onto the surviving stock item."""
+        existing = StockItem.objects.create(
+            part=self.part, location=self.dest, quantity=100
+        )
+        incoming = StockItem.objects.create(
+            part=self.part, location=self.source_loc, quantity=50
+        )
+
+        incoming.add_tracking_entry(
+            StockHistoryCode.STOCK_UPDATE,
+            self.user,
+            notes='Source tracking entry',
+        )
+
+        tracking_count = existing.tracking_info.count()
+
+        self.post(
+            self.url,
+            {
+                'items': [{'pk': incoming.pk, 'quantity': 50}],
+                'location': self.dest.pk,
+                'merge': True,
+            },
+            expected_code=201,
+        )
+
+        existing.refresh_from_db()
+
+        self.assertTrue(
+            existing.tracking_info.filter(notes='Source tracking entry').exists()
+        )
+        self.assertGreater(existing.tracking_info.count(), tracking_count)
+
+
 class StockItemDeletionTest(StockAPITestCase):
     """Tests for stock item deletion via the API."""
 
diff --git a/src/backend/InvenTree/stock/tests.py b/src/backend/InvenTree/stock/tests.py
index 94954323667e..be3c683dc368 100644
--- a/src/backend/InvenTree/stock/tests.py
+++ b/src/backend/InvenTree/stock/tests.py
@@ -722,12 +722,24 @@ def test_merge(self):
         s2 = StockItem.objects.create(part=part, quantity=20)
         s3 = StockItem.objects.create(part=part, quantity=30)
 
+        s2.add_tracking_entry(
+            StockHistoryCode.STOCK_UPDATE,
+            None,
+            notes='Merged away tracking',
+        )
+
+        tracking_before = s1.tracking_info.count()
+
         self.assertEqual(part.stock_items.count(), 3)
         s1.merge_stock_items([s2, s3])
         self.assertEqual(part.stock_items.count(), 1)
         s1.refresh_from_db()
         self.assertEqual(s1.quantity, 60)
         self.assertIsNone(s1.purchase_price)
+        self.assertTrue(
+            s1.tracking_info.filter(notes='Merged away tracking').exists()
+        )
+        self.assertGreater(s1.tracking_info.count(), tracking_before)
 
         part.stock_items.all().delete()
 
diff --git a/src/frontend/src/forms/StockForms.tsx b/src/frontend/src/forms/StockForms.tsx
index 547d2b208778..790f74d6edf2 100644
--- a/src/frontend/src/forms/StockForms.tsx
+++ b/src/frontend/src/forms/StockForms.tsx
@@ -20,7 +20,14 @@ import {
   IconUsersGroup
 } from '@tabler/icons-react';
 import { useQuery, useSuspenseQuery } from '@tanstack/react-query';
-import { type JSX, Suspense, useEffect, useMemo, useState } from 'react';
+import {
+  type JSX,
+  Suspense,
+  useCallback,
+  useEffect,
+  useMemo,
+  useState
+} from 'react';
 
 import { ActionButton } from '@lib/components/ActionButton';
 import { ApiEndpoints } from '@lib/enums/ApiEndpoints';
@@ -1319,9 +1326,21 @@ export function useRemoveStockItem(props: StockOperationProps) {
 }
 
 export function useTransferStockItem(props: StockOperationProps) {
+  const globalSettings = useGlobalSettingsState();
+
+  const fieldGenerator = useCallback(
+    (items: any[]) => ({
+      ...stockTransferFields(items),
+      merge: {
+        default: globalSettings.isSet('STOCK_MERGE_ON_TRANSFER')
+      }
+    }),
+    [globalSettings]
+  );
+
   return useStockOperationModal({
     ...props,
-    fieldGenerator: stockTransferFields,
+    fieldGenerator: fieldGenerator,
     endpoint: ApiEndpoints.stock_transfer,
     title: t`Transfer Stock`,
     successMessage: t`Stock transferred`,
diff --git a/src/frontend/src/pages/Index/Settings/SystemSettings.tsx b/src/frontend/src/pages/Index/Settings/SystemSettings.tsx
index 0078520bd943..c7a090a69d5f 100644
--- a/src/frontend/src/pages/Index/Settings/SystemSettings.tsx
+++ b/src/frontend/src/pages/Index/Settings/SystemSettings.tsx
@@ -259,6 +259,7 @@ export default function SystemSettings() {
                 'STOCK_SHOW_INSTALLED_ITEMS',
                 'STOCK_ENFORCE_BOM_INSTALLATION',
                 'STOCK_ALLOW_OUT_OF_STOCK_TRANSFER',
+                'STOCK_MERGE_ON_TRANSFER',
                 'TEST_STATION_DATA'
               ]}
             />
diff --git a/src/frontend/vite.config.ts b/src/frontend/vite.config.ts
index 627a1ade6e1b..fdbebca9972d 100644
--- a/src/frontend/vite.config.ts
+++ b/src/frontend/vite.config.ts
@@ -82,6 +82,7 @@ export default defineConfig(({ command, mode }) => {
           changeOrigin: true,
           secure: true
         }
+        
       },
       watch: {
         // Use polling only for WSL as the file system doesn't trigger notifications for Linux apps

From 9f01acaa66ff86723d966ad277425ed2c1ec44ae Mon Sep 17 00:00:00 2001
From: Neil Beukes <neilbeukes8@gmail.com>
Date: Tue, 26 May 2026 17:30:17 +0000
Subject: [PATCH 02/10] fix history when merging

---
 src/backend/InvenTree/stock/models.py      | 17 ++++++++++-------
 src/backend/InvenTree/stock/serializers.py |  5 ++---
 src/backend/InvenTree/stock/test_api.py    | 20 +++++++++++++-------
 3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/src/backend/InvenTree/stock/models.py b/src/backend/InvenTree/stock/models.py
index d3274e6a47d9..42eff73c0167 100644
--- a/src/backend/InvenTree/stock/models.py
+++ b/src/backend/InvenTree/stock/models.py
@@ -2185,7 +2185,8 @@ def find_merge_target(self, location):
             return None
 
         candidates = list(
-            StockItem.objects.filter(part=self.part, location=location)
+            StockItem.objects
+            .filter(part=self.part, location=location)
             .exclude(pk=self.pk)
             .order_by('pk')
         )
@@ -2214,8 +2215,11 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
         *This* stock item subsumes the other, which is essentially deleted:
 
         - The quantity of this StockItem is increased
-        - Tracking history for the *other* item is copied to this item
+        - Tracking history for the *other* item is copied to this item (unless copy_history=False)
         - Any allocations (build order, sales order) are moved to this StockItem
+
+        kwargs:
+            copy_history: If True (default), copy tracking from merged items. Set False for merge-on-transfer.
         """
         if isinstance(other_items, StockItem):
             other_items = [other_items]
@@ -2229,6 +2233,7 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
         user = kwargs.get('user')
         location = kwargs.get('location', self.location)
         notes = kwargs.get('notes') or ''
+        copy_history = kwargs.pop('copy_history', True)
 
         parent_id = self.parent.pk if self.parent else None
 
@@ -2270,17 +2275,15 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
                 self.parent = None
                 self.save()
 
-            self.copyHistoryFrom(other)
+            if copy_history:
+                self.copyHistoryFrom(other)
 
             if other.location:
                 location_note = _('Transferred from %(location)s') % {
                     'location': other.location.pathstring
                 }
 
-                if notes:
-                    notes = f'{notes}\n{location_note}'
-                else:
-                    notes = location_note
+                notes = f'{notes}\n{location_note}' if notes else location_note
 
             other.delete()
 
diff --git a/src/backend/InvenTree/stock/serializers.py b/src/backend/InvenTree/stock/serializers.py
index 6b857ac4033c..fe43a8047c72 100644
--- a/src/backend/InvenTree/stock/serializers.py
+++ b/src/backend/InvenTree/stock/serializers.py
@@ -1883,6 +1883,7 @@ def save(self):
                             'location': location,
                             'notes': notes,
                             'user': request.user,
+                            'copy_history': False,
                             **kwargs,
                         }
 
@@ -1897,9 +1898,7 @@ def save(self):
                             )
                             target.merge_stock_items([piece], **merge_kwargs)
                         else:
-                            target.merge_stock_items(
-                                [stock_item], **merge_kwargs
-                            )
+                            target.merge_stock_items([stock_item], **merge_kwargs)
 
                         continue
 
diff --git a/src/backend/InvenTree/stock/test_api.py b/src/backend/InvenTree/stock/test_api.py
index a4961d829d87..67eb591c12ff 100644
--- a/src/backend/InvenTree/stock/test_api.py
+++ b/src/backend/InvenTree/stock/test_api.py
@@ -2166,6 +2166,9 @@ def setUp(self):
         self.source_loc = StockLocation.objects.get(pk=5)
         self.url = reverse('api-stock-transfer')
 
+        # Remove fixture stock at the destination so merge targets are deterministic
+        StockItem.objects.filter(part=self.part, location=self.dest).delete()
+
     def test_transfer_without_merge_creates_separate_lot(self):
         """Transfer without merge leaves multiple stock rows at destination."""
         existing = StockItem.objects.create(
@@ -2219,8 +2222,8 @@ def test_transfer_with_merge_combines_lots(self):
         self.assertEqual(existing.quantity, 150)
         self.assertFalse(StockItem.objects.filter(pk=incoming.pk).exists())
 
-    def test_transfer_merge_preserves_tracking(self):
-        """Transfer merge copies tracking history onto the surviving stock item."""
+    def test_transfer_merge_does_not_copy_source_tracking(self):
+        """Transfer merge keeps destination history and adds a single merge entry."""
         existing = StockItem.objects.create(
             part=self.part, location=self.dest, quantity=100
         )
@@ -2229,9 +2232,7 @@ def test_transfer_merge_preserves_tracking(self):
         )
 
         incoming.add_tracking_entry(
-            StockHistoryCode.STOCK_UPDATE,
-            self.user,
-            notes='Source tracking entry',
+            StockHistoryCode.STOCK_UPDATE, self.user, notes='Source tracking entry'
         )
 
         tracking_count = existing.tracking_info.count()
@@ -2248,10 +2249,15 @@ def test_transfer_merge_preserves_tracking(self):
 
         existing.refresh_from_db()
 
-        self.assertTrue(
+        self.assertFalse(
             existing.tracking_info.filter(notes='Source tracking entry').exists()
         )
-        self.assertGreater(existing.tracking_info.count(), tracking_count)
+        self.assertEqual(existing.tracking_info.count(), tracking_count + 1)
+        self.assertTrue(
+            existing.tracking_info.filter(
+                tracking_type=StockHistoryCode.MERGED_STOCK_ITEMS
+            ).exists()
+        )
 
 
 class StockItemDeletionTest(StockAPITestCase):

From 47ed85e180965cb6cb004fa5e73f7f442a50f24a Mon Sep 17 00:00:00 2001
From: Neil Beukes <neilbeukes8@gmail.com>
Date: Wed, 27 May 2026 08:00:28 +0000
Subject: [PATCH 03/10] update messaging, add 'added' line in history

---
 .../InvenTree/common/setting/system.py        |  5 +-
 src/backend/InvenTree/stock/models.py         |  6 ++-
 src/backend/InvenTree/stock/serializers.py    | 14 ++++-
 src/backend/InvenTree/stock/test_api.py       | 53 +++++++++++++++----
 src/backend/InvenTree/stock/tests.py          | 15 +++---
 src/frontend/src/forms/StockForms.tsx         | 36 +++++++++----
 6 files changed, 97 insertions(+), 32 deletions(-)

diff --git a/src/backend/InvenTree/common/setting/system.py b/src/backend/InvenTree/common/setting/system.py
index ba9e60e87c97..ebe15df8ec97 100644
--- a/src/backend/InvenTree/common/setting/system.py
+++ b/src/backend/InvenTree/common/setting/system.py
@@ -788,10 +788,9 @@ class SystemSetId:
         'validator': bool,
     },
     'STOCK_MERGE_ON_TRANSFER': {
-        'name': _('Merge stock with existing stock on transfer'),
+        'name': _('Merge stock with existing stock on transfer by default'),
         'description': _(
-            'Default: when transferring stock, merge into an existing lot at the '
-            'destination if possible (uses the same rules as manual stock merge)'
+            'Default state for merge stock on transfer behaviour. (Can be changed per transfer if desired)'
         ),
         'default': False,
         'validator': bool,
diff --git a/src/backend/InvenTree/stock/models.py b/src/backend/InvenTree/stock/models.py
index 42eff73c0167..8a12bde90d3f 100644
--- a/src/backend/InvenTree/stock/models.py
+++ b/src/backend/InvenTree/stock/models.py
@@ -2251,9 +2251,12 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
                 )
                 return
 
+        merged_quantity = Decimal(0)
+
         for other in other_items:
             tree_ids.add(other.tree_id)
 
+            merged_quantity += other.quantity
             self.quantity += other.quantity
 
             if other.purchase_price:
@@ -2294,7 +2297,8 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
             notes=notes,
             deltas={
                 'location': location.pk if location else None,
-                'quantity': self.quantity,
+                'quantity': float(self.quantity),
+                'added': float(merged_quantity),
             },
         )
 
diff --git a/src/backend/InvenTree/stock/serializers.py b/src/backend/InvenTree/stock/serializers.py
index fe43a8047c72..7ca257cfcbd2 100644
--- a/src/backend/InvenTree/stock/serializers.py
+++ b/src/backend/InvenTree/stock/serializers.py
@@ -1635,7 +1635,7 @@ class StockAdjustmentItemSerializer(serializers.Serializer):
     class Meta:
         """Metaclass options."""
 
-        fields = ['pk', 'quantity', 'batch', 'status', 'packaging']
+        fields = ['pk', 'quantity', 'batch', 'status', 'packaging', 'merge']
 
     def __init__(self, *args, **kwargs):
         """Initialize the serializer."""
@@ -1709,6 +1709,15 @@ def validate_quantity(self, quantity):
         help_text=_('Packaging this stock item is stored in'),
     )
 
+    merge = serializers.BooleanField(
+        default=False,
+        required=False,
+        label=_('Merge into existing stock'),
+        help_text=_(
+            'Merge this item into existing stock at the destination if possible'
+        ),
+    )
+
 
 class StockAdjustmentSerializer(serializers.Serializer):
     """Base class for managing stock adjustment actions via the API."""
@@ -1860,13 +1869,14 @@ def save(self):
         items = data['items']
         notes = data.get('notes', '')
         location = data['location']
-        merge = data.get('merge', False)
+        default_merge = data.get('merge', False)
 
         with transaction.atomic():
             for item in items:
                 # Required fields
                 stock_item = item['pk']
                 quantity = item['quantity']
+                merge = item.get('merge', default_merge)
 
                 # Optional fields
                 kwargs = {}
diff --git a/src/backend/InvenTree/stock/test_api.py b/src/backend/InvenTree/stock/test_api.py
index 67eb591c12ff..2ffbbcd83726 100644
--- a/src/backend/InvenTree/stock/test_api.py
+++ b/src/backend/InvenTree/stock/test_api.py
@@ -2181,9 +2181,8 @@ def test_transfer_without_merge_creates_separate_lot(self):
         self.post(
             self.url,
             {
-                'items': [{'pk': incoming.pk, 'quantity': 50}],
+                'items': [{'pk': incoming.pk, 'quantity': 50, 'merge': False}],
                 'location': self.dest.pk,
-                'merge': False,
             },
             expected_code=201,
         )
@@ -2207,9 +2206,8 @@ def test_transfer_with_merge_combines_lots(self):
         self.post(
             self.url,
             {
-                'items': [{'pk': incoming.pk, 'quantity': 50}],
+                'items': [{'pk': incoming.pk, 'quantity': 50, 'merge': True}],
                 'location': self.dest.pk,
-                'merge': True,
             },
             expected_code=201,
         )
@@ -2222,6 +2220,39 @@ def test_transfer_with_merge_combines_lots(self):
         self.assertEqual(existing.quantity, 150)
         self.assertFalse(StockItem.objects.filter(pk=incoming.pk).exists())
 
+    def test_transfer_mixed_merge_per_item(self):
+        """Each transfer line can merge or move independently."""
+        existing = StockItem.objects.create(
+            part=self.part, location=self.dest, quantity=100
+        )
+        merge_incoming = StockItem.objects.create(
+            part=self.part, location=self.source_loc, quantity=30
+        )
+        separate_incoming = StockItem.objects.create(
+            part=self.part, location=self.source_loc, quantity=20
+        )
+
+        self.post(
+            self.url,
+            {
+                'items': [
+                    {'pk': merge_incoming.pk, 'quantity': 30, 'merge': True},
+                    {'pk': separate_incoming.pk, 'quantity': 20, 'merge': False},
+                ],
+                'location': self.dest.pk,
+            },
+            expected_code=201,
+        )
+
+        self.assertEqual(
+            StockItem.objects.filter(part=self.part, location=self.dest).count(), 2
+        )
+
+        existing.refresh_from_db()
+        self.assertEqual(existing.quantity, 130)
+        self.assertFalse(StockItem.objects.filter(pk=merge_incoming.pk).exists())
+        self.assertTrue(StockItem.objects.filter(pk=separate_incoming.pk).exists())
+
     def test_transfer_merge_does_not_copy_source_tracking(self):
         """Transfer merge keeps destination history and adds a single merge entry."""
         existing = StockItem.objects.create(
@@ -2240,9 +2271,8 @@ def test_transfer_merge_does_not_copy_source_tracking(self):
         self.post(
             self.url,
             {
-                'items': [{'pk': incoming.pk, 'quantity': 50}],
+                'items': [{'pk': incoming.pk, 'quantity': 50, 'merge': True}],
                 'location': self.dest.pk,
-                'merge': True,
             },
             expected_code=201,
         )
@@ -2253,11 +2283,12 @@ def test_transfer_merge_does_not_copy_source_tracking(self):
             existing.tracking_info.filter(notes='Source tracking entry').exists()
         )
         self.assertEqual(existing.tracking_info.count(), tracking_count + 1)
-        self.assertTrue(
-            existing.tracking_info.filter(
-                tracking_type=StockHistoryCode.MERGED_STOCK_ITEMS
-            ).exists()
-        )
+        merge_entry = existing.tracking_info.filter(
+            tracking_type=StockHistoryCode.MERGED_STOCK_ITEMS
+        ).first()
+        self.assertIsNotNone(merge_entry)
+        self.assertEqual(merge_entry.deltas['added'], 50.0)
+        self.assertEqual(merge_entry.deltas['quantity'], 150.0)
 
 
 class StockItemDeletionTest(StockAPITestCase):
diff --git a/src/backend/InvenTree/stock/tests.py b/src/backend/InvenTree/stock/tests.py
index be3c683dc368..aa453025f437 100644
--- a/src/backend/InvenTree/stock/tests.py
+++ b/src/backend/InvenTree/stock/tests.py
@@ -723,9 +723,7 @@ def test_merge(self):
         s3 = StockItem.objects.create(part=part, quantity=30)
 
         s2.add_tracking_entry(
-            StockHistoryCode.STOCK_UPDATE,
-            None,
-            notes='Merged away tracking',
+            StockHistoryCode.STOCK_UPDATE, None, notes='Merged away tracking'
         )
 
         tracking_before = s1.tracking_info.count()
@@ -736,11 +734,16 @@ def test_merge(self):
         s1.refresh_from_db()
         self.assertEqual(s1.quantity, 60)
         self.assertIsNone(s1.purchase_price)
-        self.assertTrue(
-            s1.tracking_info.filter(notes='Merged away tracking').exists()
-        )
+        self.assertTrue(s1.tracking_info.filter(notes='Merged away tracking').exists())
         self.assertGreater(s1.tracking_info.count(), tracking_before)
 
+        merge_entry = s1.tracking_info.filter(
+            tracking_type=StockHistoryCode.MERGED_STOCK_ITEMS
+        ).first()
+        self.assertIsNotNone(merge_entry)
+        self.assertEqual(merge_entry.deltas['added'], 50.0)
+        self.assertEqual(merge_entry.deltas['quantity'], 60.0)
+
         part.stock_items.all().delete()
 
         # Create some stock items with pricing information
diff --git a/src/frontend/src/forms/StockForms.tsx b/src/frontend/src/forms/StockForms.tsx
index 790f74d6edf2..5ae4fd3cbd07 100644
--- a/src/frontend/src/forms/StockForms.tsx
+++ b/src/frontend/src/forms/StockForms.tsx
@@ -555,6 +555,7 @@ function StockOperationsRow({
   add = false,
   setMax = false,
   merge = false,
+  transferMerge = false,
   record
 }: {
   props: TableFieldRowProps;
@@ -563,6 +564,7 @@ function StockOperationsRow({
   add?: boolean;
   setMax?: boolean;
   merge?: boolean;
+  transferMerge?: boolean;
   record?: any;
 }) {
   const statusOptions: ApiFormFieldChoice[] = useMemo(() => {
@@ -712,6 +714,17 @@ function StockOperationsRow({
                 variant={packagingOpen ? 'filled' : 'transparent'}
               />
             )}
+            {transferMerge && (
+              <ActionButton
+                size='sm'
+                icon={<InvenTreeIcon icon='merge' />}
+                tooltip={t`Merge into existing stock`}
+                onClick={() =>
+                  callChangeFn(props.idx, 'merge', !props.item?.merge)
+                }
+                variant={props.item?.merge ? 'filled' : 'transparent'}
+              />
+            )}
             <RemoveRowButton onClick={() => props.removeFn(props.idx)} />
           </Flex>
         </Table.Td>
@@ -759,9 +772,10 @@ type StockAdjustmentItem = {
   batch?: string;
   status?: number | '' | null;
   packaging?: string;
+  merge?: boolean;
 };
 
-function mapAdjustmentItems(items: any[]) {
+function mapAdjustmentItems(items: any[], mergeDefault?: boolean) {
   const mappedItems: StockAdjustmentItemWithRecord[] = items.map((elem) => {
     return {
       pk: elem.pk,
@@ -769,6 +783,7 @@ function mapAdjustmentItems(items: any[]) {
       batch: elem.batch || undefined,
       status: elem.status || undefined,
       packaging: elem.packaging || undefined,
+      merge: elem.merge ?? mergeDefault ?? false,
       obj: elem
     };
   });
@@ -776,7 +791,10 @@ function mapAdjustmentItems(items: any[]) {
   return mappedItems;
 }
 
-function stockTransferFields(items: any[]): ApiFormFieldSet {
+function stockTransferFields(
+  items: any[],
+  mergeDefault = false
+): ApiFormFieldSet {
   if (!items) {
     return {};
   }
@@ -789,7 +807,7 @@ function stockTransferFields(items: any[]): ApiFormFieldSet {
   const fields: ApiFormFieldSet = {
     items: {
       field_type: 'table',
-      value: mapAdjustmentItems(items),
+      value: mapAdjustmentItems(items, mergeDefault),
       modelRenderer: (row: TableFieldRowProps) => {
         const record = records[row.item.pk];
 
@@ -799,6 +817,7 @@ function stockTransferFields(items: any[]): ApiFormFieldSet {
             transfer
             changeStatus
             setMax
+            transferMerge
             key={record.pk}
             record={record}
           />
@@ -1329,12 +1348,11 @@ export function useTransferStockItem(props: StockOperationProps) {
   const globalSettings = useGlobalSettingsState();
 
   const fieldGenerator = useCallback(
-    (items: any[]) => ({
-      ...stockTransferFields(items),
-      merge: {
-        default: globalSettings.isSet('STOCK_MERGE_ON_TRANSFER')
-      }
-    }),
+    (items: any[]) =>
+      stockTransferFields(
+        items,
+        globalSettings.isSet('STOCK_MERGE_ON_TRANSFER')
+      ),
     [globalSettings]
   );
 

From f261bf739016fb84737ebb8b2cdf8d65c20ecc6f Mon Sep 17 00:00:00 2001
From: Neil Beukes <neilbeukes8@gmail.com>
Date: Wed, 27 May 2026 13:37:14 +0000
Subject: [PATCH 04/10] reworked history logic

---
 src/backend/InvenTree/stock/models.py      | 11 ++---------
 src/backend/InvenTree/stock/serializers.py |  1 -
 src/backend/InvenTree/stock/tests.py       |  8 --------
 3 files changed, 2 insertions(+), 18 deletions(-)

diff --git a/src/backend/InvenTree/stock/models.py b/src/backend/InvenTree/stock/models.py
index 8a12bde90d3f..f9b943969d24 100644
--- a/src/backend/InvenTree/stock/models.py
+++ b/src/backend/InvenTree/stock/models.py
@@ -2180,7 +2180,7 @@ def can_merge(self, other=None, raise_error=False, **kwargs):
         return True
 
     def find_merge_target(self, location):
-        """Find an existing stock item at *location* that can absorb this item."""
+        """Find an existing stock item at location that can absorb this item."""
         if location is None:
             return None
 
@@ -2215,11 +2215,8 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
         *This* stock item subsumes the other, which is essentially deleted:
 
         - The quantity of this StockItem is increased
-        - Tracking history for the *other* item is copied to this item (unless copy_history=False)
+        - Tracking history for the *other* item is deleted
         - Any allocations (build order, sales order) are moved to this StockItem
-
-        kwargs:
-            copy_history: If True (default), copy tracking from merged items. Set False for merge-on-transfer.
         """
         if isinstance(other_items, StockItem):
             other_items = [other_items]
@@ -2233,7 +2230,6 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
         user = kwargs.get('user')
         location = kwargs.get('location', self.location)
         notes = kwargs.get('notes') or ''
-        copy_history = kwargs.pop('copy_history', True)
 
         parent_id = self.parent.pk if self.parent else None
 
@@ -2278,9 +2274,6 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
                 self.parent = None
                 self.save()
 
-            if copy_history:
-                self.copyHistoryFrom(other)
-
             if other.location:
                 location_note = _('Transferred from %(location)s') % {
                     'location': other.location.pathstring
diff --git a/src/backend/InvenTree/stock/serializers.py b/src/backend/InvenTree/stock/serializers.py
index 7ca257cfcbd2..231fbaa29299 100644
--- a/src/backend/InvenTree/stock/serializers.py
+++ b/src/backend/InvenTree/stock/serializers.py
@@ -1893,7 +1893,6 @@ def save(self):
                             'location': location,
                             'notes': notes,
                             'user': request.user,
-                            'copy_history': False,
                             **kwargs,
                         }
 
diff --git a/src/backend/InvenTree/stock/tests.py b/src/backend/InvenTree/stock/tests.py
index aa453025f437..999fc030b0d2 100644
--- a/src/backend/InvenTree/stock/tests.py
+++ b/src/backend/InvenTree/stock/tests.py
@@ -722,20 +722,12 @@ def test_merge(self):
         s2 = StockItem.objects.create(part=part, quantity=20)
         s3 = StockItem.objects.create(part=part, quantity=30)
 
-        s2.add_tracking_entry(
-            StockHistoryCode.STOCK_UPDATE, None, notes='Merged away tracking'
-        )
-
-        tracking_before = s1.tracking_info.count()
-
         self.assertEqual(part.stock_items.count(), 3)
         s1.merge_stock_items([s2, s3])
         self.assertEqual(part.stock_items.count(), 1)
         s1.refresh_from_db()
         self.assertEqual(s1.quantity, 60)
         self.assertIsNone(s1.purchase_price)
-        self.assertTrue(s1.tracking_info.filter(notes='Merged away tracking').exists())
-        self.assertGreater(s1.tracking_info.count(), tracking_before)
 
         merge_entry = s1.tracking_info.filter(
             tracking_type=StockHistoryCode.MERGED_STOCK_ITEMS

From b5fbe784b3134931d6dc881f68fd7d356946cd02 Mon Sep 17 00:00:00 2001
From: Neil Beukes <neilbeukes8@gmail.com>
Date: Wed, 27 May 2026 13:48:22 +0000
Subject: [PATCH 05/10] removed old transfer logic

---
 src/backend/InvenTree/stock/serializers.py | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/src/backend/InvenTree/stock/serializers.py b/src/backend/InvenTree/stock/serializers.py
index 231fbaa29299..8166ecfc8796 100644
--- a/src/backend/InvenTree/stock/serializers.py
+++ b/src/backend/InvenTree/stock/serializers.py
@@ -1838,7 +1838,7 @@ class StockTransferSerializer(StockAdjustmentSerializer):
     class Meta:
         """Metaclass options."""
 
-        fields = ['items', 'notes', 'location', 'merge']
+        fields = ['items', 'notes', 'location']
 
     items = StockAdjustmentItemSerializer(many=True, require_non_zero=True)
 
@@ -1851,15 +1851,6 @@ class Meta:
         help_text=_('Destination stock location'),
     )
 
-    merge = serializers.BooleanField(
-        default=False,
-        required=False,
-        label=_('Merge into existing stock'),
-        help_text=_(
-            'Merge transferred items into existing stock items at the destination if possible'
-        ),
-    )
-
     def save(self):
         """Transfer stock."""
         request = self.context['request']
@@ -1869,14 +1860,13 @@ def save(self):
         items = data['items']
         notes = data.get('notes', '')
         location = data['location']
-        default_merge = data.get('merge', False)
 
         with transaction.atomic():
             for item in items:
                 # Required fields
                 stock_item = item['pk']
                 quantity = item['quantity']
-                merge = item.get('merge', default_merge)
+                merge = item.get('merge', False)
 
                 # Optional fields
                 kwargs = {}

From 3513a6d97d4b89e008b4f0fd643ff9c64e09e265 Mon Sep 17 00:00:00 2001
From: Neil Beukes <neilbeukes8@gmail.com>
Date: Wed, 27 May 2026 14:09:41 +0000
Subject: [PATCH 06/10] remove formatting changes from vite file

---
 src/frontend/vite.config.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/frontend/vite.config.ts b/src/frontend/vite.config.ts
index fdbebca9972d..627a1ade6e1b 100644
--- a/src/frontend/vite.config.ts
+++ b/src/frontend/vite.config.ts
@@ -82,7 +82,6 @@ export default defineConfig(({ command, mode }) => {
           changeOrigin: true,
           secure: true
         }
-        
       },
       watch: {
         // Use polling only for WSL as the file system doesn't trigger notifications for Linux apps

From ce0d3c8ae392edb5552b68d9b36679368d2ffb66 Mon Sep 17 00:00:00 2001
From: Neil Beueks <neilbeukes8@gmail.com>
Date: Mon, 1 Jun 2026 19:57:02 +0000
Subject: [PATCH 07/10] Bumped API version, added entry in docs for new global
 setting

---
 docs/docs/settings/global.md                   | 1 +
 src/backend/InvenTree/InvenTree/api_version.py | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/docs/docs/settings/global.md b/docs/docs/settings/global.md
index 752ef1b91082..f27e4b50df84 100644
--- a/docs/docs/settings/global.md
+++ b/docs/docs/settings/global.md
@@ -224,6 +224,7 @@ Configuration of stock item options
 {{ globalsetting("STOCK_SHOW_INSTALLED_ITEMS") }}
 {{ globalsetting("STOCK_ENFORCE_BOM_INSTALLATION") }}
 {{ globalsetting("STOCK_ALLOW_OUT_OF_STOCK_TRANSFER") }}
+{{ globalsetting("STOCK_MERGE_ON_TRANSFER") }}
 {{ globalsetting("TEST_STATION_DATA") }}
 
 ### Build Orders
diff --git a/src/backend/InvenTree/InvenTree/api_version.py b/src/backend/InvenTree/InvenTree/api_version.py
index 82d1c6dba367..5aeaa4e5357b 100644
--- a/src/backend/InvenTree/InvenTree/api_version.py
+++ b/src/backend/InvenTree/InvenTree/api_version.py
@@ -1,11 +1,16 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 497
+INVENTREE_API_VERSION = 498
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 INVENTREE_API_TEXT = """
 
+v498 -> 2026-06-01 : https://github.com/inventree/InvenTree/pull/12022
+    - Adds optional "merge" field to each item in the Stock Transfer API endpoint
+    - When merge is enabled, transferred stock is combined into compatible existing stock at the destination
+    - Stock merge tracking entries now include an "added" delta field;
+
 v497 -> 2026-05-27 : https://github.com/inventree/InvenTree/pull/12019
     - Adds "location" field to StockCount API endpoint
 

From f608f3364102bcbf6f2917ccf30986befca170fe Mon Sep 17 00:00:00 2001
From: Neil Beueks <neilbeukes8@gmail.com>
Date: Mon, 1 Jun 2026 20:50:28 +0000
Subject: [PATCH 08/10] removed the tracking item overwrite, Use existing
 tracking event from transfer

---
 .../InvenTree/InvenTree/api_version.py        |  2 +-
 src/backend/InvenTree/stock/models.py         | 65 ++++++++++++-------
 src/backend/InvenTree/stock/serializers.py    | 15 +++++
 src/backend/InvenTree/stock/test_api.py       | 35 ++++++++++
 4 files changed, 93 insertions(+), 24 deletions(-)

diff --git a/src/backend/InvenTree/InvenTree/api_version.py b/src/backend/InvenTree/InvenTree/api_version.py
index 5aeaa4e5357b..061c60ea486b 100644
--- a/src/backend/InvenTree/InvenTree/api_version.py
+++ b/src/backend/InvenTree/InvenTree/api_version.py
@@ -9,7 +9,7 @@
 v498 -> 2026-06-01 : https://github.com/inventree/InvenTree/pull/12022
     - Adds optional "merge" field to each item in the Stock Transfer API endpoint
     - When merge is enabled, transferred stock is combined into compatible existing stock at the destination
-    - Stock merge tracking entries now include an "added" delta field;
+    - Stock merge tracking entries now include an "added" delta field
 
 v497 -> 2026-05-27 : https://github.com/inventree/InvenTree/pull/12019
     - Adds "location" field to StockCount API endpoint
diff --git a/src/backend/InvenTree/stock/models.py b/src/backend/InvenTree/stock/models.py
index 559a9c90aa29..0834e2c67c02 100644
--- a/src/backend/InvenTree/stock/models.py
+++ b/src/backend/InvenTree/stock/models.py
@@ -2307,25 +2307,27 @@ def merge_stock_items(self, other_items, raise_error=False, **kwargs):
                 self.parent = None
                 self.save()
 
-            if other.location:
-                location_note = _('Transferred from %(location)s') % {
-                    'location': other.location.pathstring
-                }
+            other.delete()
 
-                notes = f'{notes}\n{location_note}' if notes else location_note
+        transfer_deltas = kwargs.pop('transfer_deltas', None)
 
-            other.delete()
+        tracking_deltas = {
+            'quantity': float(self.quantity),
+            'added': float(merged_quantity),
+        }
+
+        if location:
+            tracking_deltas['location'] = location.pk
+
+        if transfer_deltas:
+            tracking_deltas = {**transfer_deltas, **tracking_deltas}
 
         self.add_tracking_entry(
             StockHistoryCode.MERGED_STOCK_ITEMS,
             user,
             quantity=self.quantity,
             notes=notes,
-            deltas={
-                'location': location.pk if location else None,
-                'quantity': float(self.quantity),
-                'added': float(merged_quantity),
-            },
+            deltas=tracking_deltas,
         )
 
         # Update the location of the item
@@ -2386,6 +2388,8 @@ def splitStock(self, quantity, location=None, user=None, **kwargs):
             status: If provided, override the status (default = existing status)
             packaging: If provided, override the packaging (default = existing packaging)
             allow_production: If True, allow splitting of stock which is in production (default = False)
+            record_tracking: If False, skip tracking entries (for merge-on-transfer)
+            split_transfer_deltas: Optional dict to receive split tracking deltas
 
         Returns:
             The new StockItem object
@@ -2398,6 +2402,8 @@ def splitStock(self, quantity, location=None, user=None, **kwargs):
         """
         # Run initial checks to test if the stock item can actually be "split"
         allow_production = kwargs.get('allow_production', False)
+        record_tracking = kwargs.pop('record_tracking', True)
+        split_transfer_deltas = kwargs.pop('split_transfer_deltas', None)
 
         # Cannot split a stock item which is in production
         if self.is_building and not allow_production:
@@ -2470,15 +2476,23 @@ def splitStock(self, quantity, location=None, user=None, **kwargs):
 
         new_stock.save(add_note=False)
 
-        # Add a stock tracking entry for the newly created item
-        new_stock.add_tracking_entry(
-            StockHistoryCode.SPLIT_FROM_PARENT,
-            user,
-            quantity=quantity,
-            notes=notes,
-            location=location,
-            deltas=deltas,
-        )
+        if split_transfer_deltas is not None:
+            split_transfer_deltas.clear()
+            split_transfer_deltas.update(deltas)
+
+            if location:
+                split_transfer_deltas['location'] = location.pk
+
+        if record_tracking:
+            # Add a stock tracking entry for the newly created item
+            new_stock.add_tracking_entry(
+                StockHistoryCode.SPLIT_FROM_PARENT,
+                user,
+                quantity=quantity,
+                notes=notes,
+                location=location,
+                deltas=deltas,
+            )
 
         # Copy the test results of this part to the new one
         new_stock.copyTestResultsFrom(self)
@@ -2491,6 +2505,7 @@ def splitStock(self, quantity, location=None, user=None, **kwargs):
             notes=notes,
             location=location,
             stockitem=new_stock,
+            record_tracking=record_tracking,
         )
 
         # Rebuild the tree for this parent item
@@ -2800,7 +2815,10 @@ def take_stock(self, quantity, user, code=StockHistoryCode.STOCK_REMOVE, **kwarg
             code: The stock history code to use
             notes: Optional notes for the stock removal
             status: Optionally adjust the stock status
+            record_tracking: If False, skip creating a tracking entry
         """
+        record_tracking = kwargs.pop('record_tracking', True)
+
         # Cannot remove items from a serialized part
         if self.serialized:
             return False
@@ -2850,9 +2868,10 @@ def take_stock(self, quantity, user, code=StockHistoryCode.STOCK_REMOVE, **kwarg
 
             self.save(add_note=False)
 
-            self.add_tracking_entry(
-                code, user, notes=kwargs.get('notes', ''), deltas=deltas
-            )
+            if record_tracking:
+                self.add_tracking_entry(
+                    code, user, notes=kwargs.get('notes', ''), deltas=deltas
+                )
 
         return True
 
diff --git a/src/backend/InvenTree/stock/serializers.py b/src/backend/InvenTree/stock/serializers.py
index dc16476d15d1..ea558c7a4c69 100644
--- a/src/backend/InvenTree/stock/serializers.py
+++ b/src/backend/InvenTree/stock/serializers.py
@@ -1907,16 +1907,31 @@ def save(self):
                         }
 
                         if quantity < stock_item.quantity:
+                            transfer_deltas = {}
+
                             piece = stock_item.splitStock(
                                 quantity,
                                 location,
                                 request.user,
                                 notes=notes,
                                 allow_production=True,
+                                record_tracking=False,
+                                split_transfer_deltas=transfer_deltas,
                                 **kwargs,
                             )
+                            merge_kwargs['transfer_deltas'] = transfer_deltas
                             target.merge_stock_items([piece], **merge_kwargs)
                         else:
+                            transfer_deltas = {'stockitem': stock_item.pk}
+
+                            if location:
+                                transfer_deltas['location'] = location.pk
+
+                            for field_name in StockItem.optional_transfer_fields():
+                                if field_name in kwargs:
+                                    transfer_deltas[field_name] = kwargs[field_name]
+
+                            merge_kwargs['transfer_deltas'] = transfer_deltas
                             target.merge_stock_items([stock_item], **merge_kwargs)
 
                         continue
diff --git a/src/backend/InvenTree/stock/test_api.py b/src/backend/InvenTree/stock/test_api.py
index 7b7316cc1778..ebe1a0e4bd01 100644
--- a/src/backend/InvenTree/stock/test_api.py
+++ b/src/backend/InvenTree/stock/test_api.py
@@ -2448,6 +2448,7 @@ def test_transfer_merge_does_not_copy_source_tracking(self):
             StockHistoryCode.STOCK_UPDATE, self.user, notes='Source tracking entry'
         )
 
+        incoming_pk = incoming.pk
         tracking_count = existing.tracking_info.count()
 
         self.post(
@@ -2471,6 +2472,40 @@ def test_transfer_merge_does_not_copy_source_tracking(self):
         self.assertIsNotNone(merge_entry)
         self.assertEqual(merge_entry.deltas['added'], 50.0)
         self.assertEqual(merge_entry.deltas['quantity'], 150.0)
+        self.assertEqual(merge_entry.deltas['stockitem'], incoming_pk)
+        self.assertEqual(merge_entry.deltas['location'], self.dest.pk)
+
+    def test_transfer_merge_partial_reuses_split_transfer_deltas(self):
+        """Partial merge reuses split transfer deltas on the merge tracking entry."""
+        existing = StockItem.objects.create(
+            part=self.part, location=self.dest, quantity=100
+        )
+        incoming = StockItem.objects.create(
+            part=self.part, location=self.source_loc, quantity=100
+        )
+
+        self.post(
+            self.url,
+            {
+                'items': [{'pk': incoming.pk, 'quantity': 30, 'merge': True}],
+                'location': self.dest.pk,
+            },
+            expected_code=201,
+        )
+
+        incoming.refresh_from_db()
+        self.assertEqual(incoming.quantity, 70)
+
+        merge_entry = existing.tracking_info.filter(
+            tracking_type=StockHistoryCode.MERGED_STOCK_ITEMS
+        ).first()
+        self.assertEqual(merge_entry.deltas['stockitem'], incoming.pk)
+        self.assertEqual(merge_entry.deltas['location'], self.dest.pk)
+        self.assertFalse(
+            incoming.tracking_info.filter(
+                tracking_type=StockHistoryCode.SPLIT_CHILD_ITEM
+            ).exists()
+        )
 
 
 class StockItemDeletionTest(StockAPITestCase):

From 3cbf2f4fd4ac80352eb007847df5bc0414b1f771 Mon Sep 17 00:00:00 2001
From: Neil Beueks <neilbeukes8@gmail.com>
Date: Fri, 5 Jun 2026 13:06:05 +0000
Subject: [PATCH 09/10] run pre-commit checks

---
 src/backend/InvenTree/InvenTree/api_version.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/InvenTree/InvenTree/api_version.py b/src/backend/InvenTree/InvenTree/api_version.py
index 4fcc2b9b2ba4..3c2f9c8bd1f2 100644
--- a/src/backend/InvenTree/InvenTree/api_version.py
+++ b/src/backend/InvenTree/InvenTree/api_version.py
@@ -10,7 +10,7 @@
 v500 -> 2026-06-01 : https://github.com/inventree/InvenTree/pull/12022
     - Adds optional "merge" field to each item in the Stock Transfer API endpoint
     - When merge is enabled, transferred stock is combined into compatible existing stock at the destination
-    - Stock merge tracking entries now include an "added" delta field
+    - Stock merge tracking entries now include an "added" delta field.
 
 v499 -> 2026-06-01 : https://github.com/inventree/InvenTree/pull/12057
     - Fixes search field issues on the BarcodeScanHistory API endpoint

From ff8b9cf77933df050c1db02981e873a357b720e7 Mon Sep 17 00:00:00 2001
From: Matthias Mair <code@mjmair.com>
Date: Sat, 6 Jun 2026 17:36:17 +0200
Subject: [PATCH 10/10] fix style

---
 src/frontend/src/forms/StockForms.tsx | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/frontend/src/forms/StockForms.tsx b/src/frontend/src/forms/StockForms.tsx
index 92ab428a347a..a0de3608b250 100644
--- a/src/frontend/src/forms/StockForms.tsx
+++ b/src/frontend/src/forms/StockForms.tsx
@@ -35,7 +35,14 @@ import {
 import { useQuery, useSuspenseQuery } from '@tanstack/react-query';
 
 import dayjs from 'dayjs';
-import { type JSX, Suspense, useCallback, useEffect, useMemo, useState } from 'react';
+import {
+  type JSX,
+  Suspense,
+  useCallback,
+  useEffect,
+  useMemo,
+  useState
+} from 'react';
 import { useFormContext } from 'react-hook-form';
 import { useNavigate } from 'react-router-dom';
 import { api } from '../App';